Cholecystokinin (CCK) is a brain/gastrointestinal tract hormone and has a close connection with the central nervous system and the gastrointestinal tract. CCK receptors are categorized into two groups: CCK-A receptor which is found primarily within components of the digestive tract such as the pancreas or the biliary system and CCK-B receptor which is found in the brain. CCK-A receptor is considered to significantly participate in control of gastrointestinal motility and pancreatic juice system. CCK-B receptor is considered to significantly participate in appetite regulation and psychic activities.
On the other hand, Gastrin, known as a hormone stimulating gastric acid secretion and CCK have in common five C-terminal amino acid residues. Therefore, both are called members of the gastrin/CCK family. Gastrin receptor, which may be found in the gastrointestinal tract, pancreas, and the biliary system, are primarily found in gastric mucosal cells (parietal cells) and participate in the control of gastric acid and pepsin secretion. The gene encoding CCK-B receptor and gastrin receptor were cloned, and as a result, it was found that the amino acid sequences of the two receptors are identical (Y-M. Lee, et al., J. Biological Chem. 268 (11) 8164-8169, 1993).
As described hereinbefore, there are two groups of CCK receptors, and the CCK-B receptor is considered to be identical to the gastrin receptor. Various diseases are considered to manifest themselves through these receptors.
Accordingly, development of compounds having strong binding inhibition against one of CCK-A or gastrin (CCK-B) group of receptors is desired.
Accordingly, a general object of the present invention is to provide a compound exhibiting strong binding inhibition against members of either the gastrin (CCK-B) receptor or the CCK-A receptor.